In situ radiometric and exposure age dating of the martian surface

K.A. Farley*, C. Malespin, P. Mahaffy, J.P. Grotzinger, P.M. Vasconcelos, R.E. Milliken, M. Malin, K.S. Edgett, A.A. Pavlov, J.A. Hurowitz, J.A. Grant, H.B. Miller, R. Arvidson, L. Beegle, F. Calef, P.G. Conrad, W.E. Dietrich, J. Eigenbrode, R. Gellert, S. GuptaV. Hamilton, D.M. Hassler, K.W. Lewis, S.M. McLennan, D. Ming, Rafael Navarro-Gonzalez, Susanne P. Schwenzer, A. Steele, E.M. Stolper, D. Y. Sumner, David T. Vaniman, Ashwin Vasavada, K.H. Williford, R.F. Wimmer-Schweingruber, MSL Science Team

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

204 Citations (Scopus)


We determined radiogenic and cosmogenic noble gases in a mudstone on the floor of Gale Crater. A K-Ar age of 4.21 ± 0.35 billion years represents a mixture of detrital and authigenic components and confirms the expected antiquity of rocks comprising the crater rim. Cosmic-ray-produced 3He, 21Ne, and 36Ar yield concordant surface exposure ages of 78 ± 30 million years. Surface exposure occurred mainly in the present geomorphic setting rather than during primary erosion and transport. Our observations are consistent with mudstone deposition shortly after the Gale impact or possibly in a later event of rapid erosion and deposition. The mudstone remained buried until recent exposure by wind-driven scarp retreat. Sedimentary rocks exposed by this mechanism may thus offer the best potential for organic biomarker preservation against destruction by cosmic radiation.
Original languageEnglish
Article number1247166
Number of pages6
Issue number6169
Early online date9 Dec 2013
Publication statusPublished - 24 Jan 2014


  • Aerospace Engineering
  • Martian surface


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